Friction stir welded hollow airfoils and method therefor

Abstract

A hollow component for gas turbine engine, for example an outlet guide vane, is assembled from a body having at recessed pocket formed therein, and an aerodynamic cover bonded over the pocket. Both the cover and the body are constructed from materials which are not readily fusion weldable. The cover is attached to the body by a solid state bonding process, for example friction stir welding. The hollow component may also be built up from multiple individual components which are bonded to each other by a solid state bonding process such as friction stir welding.

1. A hollow airfoil, comprising:
 a metallic body having opposed pressure and suction sides, a root, a tip, and spaced-apart leading and trailing edges, said body having a recessed first pocket formed in a selected one of said pressure and suction sides; 
 a filler material disposed in said first pocket; and 
 a first metallic cover having an outer peripheral edge, an inner surface, and an outer surface, said outer surface defining at least a portion of said selected one of said pressure or suction sides, wherein said first cover is attached to said body by a solid state bond. 
 
   
   
     2. The hollow airfoil of  claim 1  wherein said first pocket includes at least one upstanding rib which extends in a direction from said root to said tip, and said first cover is attached to said rib by a solid state bond. 
   
   
     3. The hollow airfoil of  claim 1  wherein said body includes a recessed ledge extending around the periphery of said first pocket which is adapted for receiving said first cover such that said outer surface of said first cover fits substantially flush with said selected one of said pressure and suction sides of said airfoil. 
   
   
     4. The hollow airfoil of  claim 1  wherein said cover and said body comprise a 7000 series aluminum alloy. 
   
   
     5. The hollow airfoil of  claim 4  wherein said cover and said body comprise a 7075 aluminum alloy. 
   
   
     6. The hollow airfoil of  claim 1  wherein said airfoil forms part of a fan outlet guide vane. 
   
   
     7. The hollow airfoil of  claim 1  wherein said solid state bond is a friction stir weld. 
   
   
     8. The hollow airfoil of  claim 1  wherein said filler material is a honeycomb structure. 
   
   
     9. The hollow airfoil of  claim 1  wherein said filler material is bonded to at least one of said first pocket and said first cover with an adhesive. 
   
   
     10. The hollow airfoil of  claim 1  further comprising:
 a second recessed pocket formed in the other one of said pressure and suction sides; and 
 a second metallic cover having an outer peripheral edge, as inner surface, and an outer surface, said outer surface defining at least a portion of said other one of said pressure or suction sides, wherein said second cover is attached to said body by a solid state bond. 
 
   
   
     11. The hollow airfoil of  claim 10  wherein said body includes a recessed ledge extending around the periphery of said second pocket which is adapted for receiving said second cover such that said outer surface of said second cover fits substantially flush with said other one of said pressure and suction sides of said airfoil. 
   
   
     12. The hollow airfoil of  claim 10  further comprising a filler material disposed in said second pocket. 
   
   
     13. The hollow airfoil of  claim 12  wherein said filler material is a honeycomb structure. 
   
   
     14. The hollow airfoil of  claim 12  wherein said filler material is bonded to at least one of said second pocket and said second cover with an adhesive. 
   
   
     15. A method of making a hollow airfoil, comprising:
 providing an airfoil-shaped body having spaced-apart leading and trailing edges, spaced-apart pressure and suction sides, a root, and a tip, a selected one of said pressure and suction sides having a first pocket formed therein; 
 providing a first cover with a perimeter matching the perimeter of said first pocket, and an outer surface defining at least a portion of said selected one of said pressure or said suction sides; 
 placing a filler material in said first pocket; 
 placing said cover in said first pocket; and 
 joining said first cover to said body by friction stir welding such that said first pocket is sealed from a surrounding environment. 
 
   
   
     16. The method of  claim 15  wherein the step of placing said first cover in said first pocket further comprises placing said first cover against a recessed ledge formed in said body which extends around the periphery of said first pocket, the depth of said first pocket being selected to position said first cover such that said outer surface of said first cover fits substantially flush with said selected one of said pressure and suction sides of said airfoil. 
   
   
     17. The method of  claim 15  wherein said filler material is a honeycomb structure. 
   
   
     18. The method of  claim 15  further comprising bonding said filler material to at least one of said first pocket and said first cover with an adhesive. 
   
   
     19. The method of  claim 15  further comprising:
 forming a second recessed pocket in the other one of said pressure and suction sides of said body; 
 providing a second cover with a perimeter matching the perimeter of said second pocket, and an outer surface defining at least a portion of the other one of said pressure or said suction sides; 
 placing said cover in said second pocket; and 
 joining said second cover to said body by friction stir welding such that said second pocket is sealed from a surrounding environment. 
 
   
   
     20. The method of  19  further comprising placing a filler material in said second pocket. 
   
   
     21. The method of  claim 20  wherein said filler material is a honeycomb structure. 
   
   
     22. The method of  claim 20  further comprising bonding said filler material bonded to at least one of said second pocket and said second cover with an adhesive. 
   
   
     23. The method of  claim 15  wherein said first pocket includes at least one upstanding rib which extends in a direction from said root to said tip, and said first cover is attached to said rib by friction stir welding. 
   
   
     24. The method of  claim 15  wherein said first cover and said body comprise a 7000 series aluminum alloy. 
   
   
     25. The method of  claim 24  wherein said first cover and said body comprise a 7075 aluminum alloy. 
   
   
     26. The method of  claim 15  wherein said airfoil forms part of a fan outlet guide vane. 
   
   
     27. A hollow airfoil having opposed pressure and suction sides, a root, a tip, and spaced-apart leading and trailing edges, said airfoil comprising:
 a metallic pressure side wall extending from said leading edge to said trailing edge; 
 a metallic suction side wall extending from said leading edge to said trailing edge, said suction side wall disposed in spaced-apart relation to said pressure side wall; 
 a metallic leading edge spacer extending from said root to said tip, the leading edge spacer separate from and disposed between said pressure and suction side walls; and 
 a metallic trailing edge spacer extending from said root to said tip, the trailing edge spacer separate from and disposed between said pressure and suction side walls; 
 wherein said pressure side wall and said suction side wall are attached to said leading and trailing edge spacers by a plurality of solid state bonds. 
 
   
   
     28. The hollow airfoil of  claim 27  further comprising at least one metallic internal spacer disposed between said pressure and suction side walls, said internal spacer being attached to each of said pressure and suction side walls by a solid state bond. 
   
   
     29. The hollow airfoil of  claim 28  wherein said internal spacer extends from said root to said tip of said airfoil. 
   
   
     30. The hollow airfoil of  claim 27  wherein said pressure side wall, said suction side wall, said reading edge spacer, and said trailing edge spacer comprise a 7000 series aluminum alloy. 
   
   
     31. The hollow airfoil of  claim 27  wherein said pressure side wall, said suction side wall, said leading edge spacer, and said trailing edge spacer comprise a 7075 aluminum alloy. 
   
   
     32. The hollow airfoil of  claim 27  wherein said airfoil forms part of a fan outlet guide vane. 
   
   
     33. The hollow airfoil of  claim 27  wherein said solid state bond is a friction stir weld.